Long-term effectiveness of heavy metal(loid) stabilization: Development of an assessing method.

In-situ stabilization technology offers a cost-effective solution for the remediation of heavy metal(loid) (HM) contaminated soils. However, the lack of a reliable method to assess the long-term effectiveness of HM stabilization significantly impedes the practical application of this technology. To address this gap, we have devised an innovative method that integrates acid rain leaching with dry-wet alternation to evaluate the long-term effectiveness of HM stabilization.

Enantioselective Synthesis of Hydrindanes via Palladium-Catalyzed Asymmetric Desymmetrization of Cyclohexadiene Derivatives.

We herein disclose a strategy for the asymmetric desymmetrization of cyclohexadiene derivatives via a palladium-catalyzed Heck and tandem Heck/Tsuji-Trost allylic alkoxylation reaction. By employing DCE as the solvent, we obtained a variety of chiral hydrindanes containing an all-carbon quaternary carbon center and a tertiary carbon chiral center in good yields with excellent enantioselectivities. With alcohols as the solvent, the valuable chiral hydrindanes with one quaternary stereocenter and two tertiary centers were constructed with a high level of enantioinduction.

Site-Selective Electrophilic Trifluoromethylthiolation for the Synthesis of C5- or C7-SCF-Substituted Indolines.

We report herein an efficient and site-selective electrophilic trifluoromethylthiolation of indolines. In the absence of any catalyst or additive, C5-selective trifluoromethylthiolation could proceed at room temperature. With palladium used as the catalyst, the selectivity was reversed completely, giving C7-selecive trifluoromethylthiolated products.

Efficient remediation of different concentrations of Cr-contaminated soils by nano zero-valent iron modified with carboxymethyl cellulose and biochar.

Nano zero-valent iron (nZVI) is widely used in soil remediation due to its high reactivity. However, the easy agglomeration, poor antioxidant ability and passivation layer of Fe-Cr coprecipitates of nZVI have limited its application scale in Cr-contaminated soil remediation, especially in high concentration of Cr-contaminated soil. Herein, we found that the carboxymethyl cellulose on nZVI particles could increase the zeta potential value of soil and change the phase of nZVI.

Palladium-Catalyzed Asymmetric Desymmetrization for the Simultaneous Construction of Chiral Phosphorus and Quaternary Carbon Stereocenters.

A palladium-catalyzed asymmetric tandem Heck and carbonylation of bisallyl-phosphine oxides has been developed. This desymmetrization process provided an efficient route to the simultaneous synthesis of a chiral P-stereogenic center and a chiral quaternary carbon stereocenter in good yields with good diastereo- and enantioselectivities.

Palladium-Catalyzed Defluorinative Alkylation of -Difluoroalkenes with Cyclopropanols: Stereoselective Synthesis of γ-Fluorinated γ,δ-Unsaturated Ketones.

A palladium-catalyzed defluorinative alkylation of -difluoroalkenes with cyclopropyl alcohols was developed. A range of γ-fluorinated γ,δ-unsaturated ketones were constructed in good yields with excellent stereoselectivities. In addition, by base-mediated intramolecular nucleophilic vinylic substitution (SV), the products could be further transformed to 2,5-dimethylenetetrahydrofurans and analogues with excellent stereoselectivities.

Palladium-Catalyzed Atroposelective Suzuki-Miyaura Coupling to Construct Axially Chiral Tetra-Substituted α-Boryl Styrenes.

Palladium-catalyzed Suzuki-Miyaura (SM) coupling is a valuable method for forming C─C bonds, including those between aryl moieties. However, achieving atroposelective synthesis of axially chiral styrenes via SM coupling remains challenging. In this study, a palladium-catalyzed atroposelective Suzuki-Miyaura coupling between gem-diborylalkenes and aryl halides is presented.

Effects of remediation agents on rice and soil in toxic metal(loid)s contaminated paddy fields: A global meta-analysis.

Toxic metal(loid)s contamination of paddy soil is a nonnegligible issue and threatens food safety considering that it is transmitted via the soil-plant system. Applying remediation agents could effectively inhibit the soil available toxic metal(loid)s and reduce their accumulation in rice. To comprehensively quantify how remediation agents impact the accumulation of Cd/Pb/As in rice, rice growth and yield, the accumulation of available Cd/Pb/As in paddy soil, and soil characteristics, 50 peer-reviewed publications were selected for meta-analysis.

Atroposelective Synthesis of Axially Chiral Diaryl Ethers by -Heterocyclic-Carbene-Catalyzed Sequentially Desymmetric/Kinetic Resolution Process.

We describe herein an -heterocyclic-carbene-catalyzed atroposelective synthesis of axially chiral diaryl ethers. Through a sequentially enantioselective desymmetric process and a kinetic resolution process, the products could be constructed in good yields with excellent enantiopurities. Both alcohols and phenols were compatible with this catalytic system.

The effects of iron-based nanomaterials (Fe NMs) on plants under stressful environments: Machine learning-assisted meta-analysis.

Mitigating the adverse effects of stressful environments on crops and promoting plant recovery in contaminated sites are critical to agricultural development and environmental remediation. Iron-based nanomaterials (Fe NMs) can be used as environmentally friendly nano-fertilizer and as a means of ecological remediation. A meta-analysis was conducted on 58 independent studies from around the world to evaluate the effects of Fe NMs on plant development and antioxidant defense systems in stressful environments.

Enhanced fertilizer utilization and heavy metals immobilization by ball-milling bentonite with NHCl: Experiments and DFT calculations.

Over-application of nitrogen fertilizer induces soil acidification, which activates heavy metals availability and poses significant challenge to crop production and food safety. In this study, we prepared a clay-based material by ball-milling bentonite with NHCl (NHCl@bentonite) and assessed its synergistic performance in enhancing nitrogen fertilizer utilization efficiency, immobilizing heavy metals, and improving crop yield and safety. The results showed that the optimal performance of NHCl@bentonite was achieved by milling bentonite with NHCl at a 4:1 mass ratio for 9 h.

Is Cr(III) re-oxidation occurring in Cr-contaminated soils after remediation: Meta-analysis and machine learning prediction.

Whether Cr(III) in Cr(III)-containing sites formed after Cr(VI) reduction and stabilization remediation are re-oxidized and pose toxicity risks again has been a growing concern. In this study, 1030 data were collected to perform a meta-analysis to clarify the effects of various factors (oxidant type, soil and Cr(III) solid compound properties, aging conditions, and testing methods) on Cr(III) oxidation. We observed that the soil properties of clay, pH ≥ 8, the lower CEC capacity, easily reducible Mn content, and Cr(III) content, and the higher Eh value and Fe content can promote the re-oxidation of Cr(III).

Degradation of trichloroethylene by biochar supported nano zero-valent iron (BC-nZVI): The role of specific surface area and electrochemical properties.

Direct electron transfer and the involvement of atomic hydrogen (H) are considered the main mechanisms for reductive dechlorination promoted by nano zero-valent iron (nZVI) supported on highly conductive carbon. It is still unclear how precisely H, the specific surface area, and the electrochemical characteristics contribute to biochar supported nano zero-valent iron (BC-nZVI) activity in chlorinated hydrocarbon contaminant removal. In this study, a range of BC-nZVIs were prepared by a liquid-phase reduction process, and the contributions of specific surface area and electrochemical performance to H generation and electron transfer have been assessed.

Enantioselective Synthesis of Bicyclo[3.2.1]octadienes via Palladium-Catalyzed Intramolecular Alkene-Alkyne Coupling Reaction.

Bicyclo[3.2.1]octadiene compounds and derivatives exist in a number of natural products and bioactive compounds.

Enhanced remediation of Cr(VI)-contaminated soil by modified zero-valent iron with oxalic acid on biochar.

Hexavalent chromium (Cr(VI)) is carcinogenic and widely presented in soil. In this study, modified zero-valent iron (ZVI) with oxalic acid on biochar (OA-ZVI/BC) was prepared using wet ball milling method for the remediation of Cr(VI)-contaminated soil. Microscopic characterizations showed that ZVI were distributed on the biochar uniformly and confirmed the enhanced interface interaction between biochar and ZVI by wet ball milling.

Copper-Catalyzed Enantioselective and Regiodivergent Allylation of Ketones with Allenylsilanes.

We report herein a regiodivergent and enantioselective allyl addition to ketones with allenylsilanes through copper catalysis. With the combination of CuOAc, a Josiphos-type bidentate phosphine ligand and PhSiH , allyl addition to a variety of ketones furnishes branched products in excellent enantioselectivities. The regioselectivity is completely reversed by employing the P-stereogenic ligand BenzP*, affording the linear products with excellent enantioselectivities and good Z-selectivities.

Effects of soil amendments on Cd and As mobility in the soil-rice system and their distribution in the grain.

The accumulation, mobilization, and distribution of toxic metal(loid)s in rice are key factors that affect food security and determine bio-utilization patterns. In this study, five soil amendments with different components were used in paddy fields to study the key factors: organic amendments: (1) polyaspartic acid (OA1) and (2) organic fertilizer (OA2); inorganic amendments: (3) kaolinite (IA1) and (4) magnesium slag (IA2); and organic-inorganic composite amendments: (5) modified biochar/quicklime (OIA). Although the Cd and As exhibited opposite chemical dissolution behaviors, IA1/OIA, can simultaneously reduce their accumulation and transfer coefficients in rice tissues, while other amendments only work for one of them.

Effects of the application of nanoscale zero-valent iron on plants: Meta analysis, mechanism, and prospects.

In order to determine the ideal conditions for the application of nanoscale zero-valent iron (nZVI) in agricultural production, this review studies the effects of nZVI application on plant physiological parameters, presents its mechanism and prospective outcomes. In this research, it was observed that the application of nZVI had both favorable and unfavorable effects on plant growth, photosynthesis, oxidative stress, and nutrient absorption levels. Specifically, the application of nZVI significantly increased the biomass and length of plants, and greatly reduced the germination rate of seeds.

Internal Electric Field-Modulated Charge Migration Behavior in MoS /MIL-53(Fe) S-Scheme Heterojunction for Boosting Visible-Light-Driven Photocatalytic Chlorinated Antibiotics Degradation.

Inadequate photo-generated charge separation, migration, and utilization efficiency limit the photocatalytic efficiency. Herein, a MoS /MIL-53(Fe) photocatalyst/activator with the S-scheme heterojunction structure is designed and the charge migration behavior is modulated by the internal electric field (IEF). The IEF intensity is enhanced to 40 mV by modulating band bending potential and the depletion layer length of MoS .

Atroposelective Synthesis of Axially Chiral Styrenes by Platinum- Catalyzed Stereoselective Hydrosilylation of Internal Alkynes.

Hydrofunctionalization of alkynes is one of the most efficient ways to access axially chiral styrenes with open-chained olefins. While great advances have been achieved for 1-alkynylnaphthalen-2-ols and analogues, atroposelective hydrofunctionalization of unactivated internal alkynes lags. Herein we reported a platinum-catalyzed atroposelective hydrosilylation of unactivated internal alkynes for the first time.